Abstract Introduction Anatomical variations of the tracheobronchial tree are uncommon, with most being asymptomatic and discovered incidentally on imaging or bronchoscopy. Supernumerary bronchi are a subset of these congenital anomalies that arise from the trachea or main bronchi. Here, we present a case of a woman with right middle lobe bronchiectasis, in whom bronchoscopy revealed a supernumerary bronchus at the level of the main carina. Case A 77-year-old woman from Taiwan, with no history of smoking, was evaluated in our outpatient pulmonary office for chronic cough, productive of white sputum. Imaging revealed right middle lobe (RML) bronchiectasis, bronchial wall thickening associated with mucoid impaction, and clustered tree-in-bud opacities in the right lower lobe (RLL). Bronchoscopy revealed mucus plugging in the medial and lateral segments of the RML which were lavaged and sent for cultures analysis. During bronchoscopy, an anomalous opening at the level of the main carina was discovered, suspicious for supernumerary bronchus, ending in a blind pouch. There was no evidence of mucoid impaction or infection within the opening. It was not traversed due to its small orifice and potential for harm. AFB cultures from the RML eventually speciated, growing Mycobacterium avium complex. Discussion The prevalence of supernumerary bronchi is uncommon, estimated to be 0.99% in the general population and higher in children (2.55%) than adults (0.5%). The occurrence of supernumerary bronchi at the level of the carina is exceedingly rare in the adult population, with very few documented cases in the literature. Supernumerary bronchi may end blindly, communicate with segmental bronchi, or be associated with ventilated lung parenchyma. Although mostly asymptomatic, their identification can be clinically relevant. Burdensome symptoms such as chronic cough and wheezing, in addition to complications such as hemoptysis and recurrent infections can occur. In our case, the carinal bronchus was not believed to be clinically significant, but its recognition may allow for early intervention if sequelae occur in the future. This abstract is funded by: None
Popovich et al. (Fri,) studied this question.